To assess the changes of calcium metabolism and osteopathy in patients with diabetes. Serum Ca, P, AKP, PTH, CT, plasma fasting blood glucose (FBG) and HbA1 as well as X-ray film of the lumbar spine were measured in 30 diabetes patients; 11 were IDDM and 19 were NIDDM as compared to controls matched for age and sex. There were no significant differences in Ca, P, and CT values in serum between the IDDM and NIDDM patients and controls, whereas the serum levels of PTH and AKP were significant increased in IDDM patients. The incidence of osteoporosis which was shown by X-ray film in NIDDM patients was higher than in those of controls. No correlation between PTH value and osteoporosis or clinical control of diabetes was observed.